1. Field of the Invention
The present invention relates generally to a Wireless Local Area Network (WLAN), more particularly, to a method and apparatus for improving unbalance of service of stations located at a cell edge in a WLAN.
2. Description of the Related Art
Commonly, a WLAN includes a station (e.g., a personal computer, a notebook computer, a Personal Digital Assistant (PDA), etc.) equipped with a wireless Network Interface Card (NIC), and an Access Point (AP) that acts as a gateway between the station and an Internet Protocol (IP) network. The AP performs a similar function as a hub of a wired LAN. Twenty five to fifty stations may simultaneously access the AP in order to receive service from the AP in an area, commonly referred to as a “hot spot,” of a radius of about 20 meters to 150 meters per AP.
Unlike a wired LAN that enables a flow of data only through a physical connection, a WLAN has additional security considerations because of the use of a wirelessly transmitted broadcasting medium. Additionally, a WLAN has mobility considerations for a station traveling between a serving AP and a target AR
In order to ensure mobility, an Institute Electrical and Electronics Engineers (IEEE) 802.11 task group now proposes an Inter Access Point Protocol (IAPP). The IAPP receives information on a detected station from a lower layer and delivers state information on the moving station to a new AP from a previous AP of the moving station.
In the conventional art, a station accessing an AP becomes a subject of handover determination, scans peripheral APs considering, for example, signal strengths of the APs, selects a target AP using the scanning results, and handovers to the target AP. However, the station determines handover based on a signal strength of an AP and thus, despite the signal strength of the AP being equal to or greater than a threshold value from a perspective of the station, this determination does not actually take into account the signal strength from a perspective of the AP. That is, this determination merely assumes that a signal strength of the station is equal to or less than a threshold value at a side of the AP. Consequently, unbalance of service of an uplink and a downlink may occur. More specifically, because of a great difference between a transmit power of the AP and a transmit power of the station, there is a high probability of occurrence of the service unbalance in a cell edge.
Accordingly, there may be a problem in which stations located at a cell edge can normally receive voice and data packets from the other station, but the AP fails to successfully receive voice and data packets from the stations because of the relatively small signal strengths of the stations. Therefore, there is a need for a method and apparatus for improving this unbalance of service at a cell edge in a WLAN.